1. Technical Field of the Invention
The present invention relates to digital subscriber loop (DSL) systems and, more particularly, to a method and apparatus for adapting the duplexing ratio implemented by a DSL system to meet application needs.
2. Description of Related Art
With the advent of inexpensive computers, the demand for residential broadband services has been increasing due to the widespread use of computers and the rapid development of computer networks. As a result, various Digital Subscriber Line (DSL) services have been proposed to make better use of the existing copper loop telecommunications infrastructure for the global information highway. DSL includes a large family of services including: asymmetrical DSL (ADSL); symmetrical DSL (SDSL); high data rate DSL (HDSL); and very high data rate DSL (VDSL), collectively and generally referred to as x-type digital subscriber line (xDSL) technologies.
The phrase “DSL duplexing ratio” refers to the ratio between upstream and downstream bandwidth used on the DSL loop to carry data communications. Currently, the duplexing ratio for a DSL modem implementing one specific xDSL technology is fixed. By this it is meant that the xDSL technology used by the DSL modem determines and specifies how the overall bandwidth of the physical loop link is to be shared between the upstream and downstream transmission directions, and this sharing relationship cannot be changed or adjusted.
For example, the bandwidth of an ADSL link is asymmetrically duplexed, with more bandwidth being allocated to the downstream transmission direction. More specifically, the fixed DSL duplexing ratio for ADSL is typically on the order of 1:8 to 1:4. The basic assumption for the implementation of ADSL technology is that the user will be mainly receiving data from Central Office (CO), and thus a greater portion of the available DSL bandwidth is allocated to the downstream.
While ADSL technology is likely to be the most attractive option for residential users, SDSL is more popular with business users and telecommuters. The reason for this is that the SDSL technology equally divides the available bandwidth between the upstream and downstream directions (duplexing ratio of 1:1). This allows users access to sufficient bi-directional bandwidth to efficiently send and receive large files.
The fixed duplexing ratios of xDSL technologies, however, cannot be adjusted to account for the type of the user application at issue and the bit rates needed by the DSL upstream and downstream signals. It is well recognized by those skilled in the art that different DSL duplexing ratios may be desired by the same user for different DSL applications. For example, when a video conference application is activated by a user through a DSL link, a symmetrical link is optimal. However, an asymmetrical link is desired when an upload application is launched by the user at a later time. What should be noted is that the high data rate direction is not necessarily always the downstream direction, and the duplexing ratio between upstream and downstream bandwidth often times needs to be varied on an application-by-application basis to best suit the needs of the user.
For users of applications that have similar DSL bandwidth requirements, the xDSL technologies provide acceptable service. However, due to the fixed duplexing ratios of xDSL technologies, users of applications that have variable bandwidth range needs may find themselves inefficiently utilizing the available spectrum resources for some time with an unfavorable duplexing ratio. It would be a significant benefit to the user if the DSL duplexing ratio could be adapted to the upstream and downstream communication needs of the application.